# Help with Coefficient of Variation

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#### bp0001

I am trying to compare the mortality rate of a current population to the mortality rate of a prior population. I am evaluating the statistic

X=(number of deaths in current population) / (prior mortality rate*current exposure)

Is the coefficient of variation

1/sqrt(number of deaths of current population)

This was given to me by someone, but I can't work out the logic. If it is, can you tell me why?

R

#### Rick Goodson

bp0001,

I am not sure I understand your question. Never the less...

The Coefficient of Variation is a relative measure of dispersion. It is the standard deviation divided by the mean multiplied by 100 to give a percentage value. This measure can not be used when the data takes both positive and negative values. It is usually associated with Log-Normal distributions where the values are all positive and are markedly skewed such as the survival times of bacteria when treated with a disinfectant.

Hope this helps.

Rick